Novel oxidative routes to -arylpyridoindazolium salts.

A novel facile approach to -arylpyridoindazolium salts is proposed, based on direct oxidation of the -pyridine substituted diarylamines, either using bis(trifluoroacetoxy)iodobenzene as an oxidant, or electrochemically, via potentiostatic oxidation. Electrochemical synthesis occurs under mild conditions; no chemical reagents are required except electric current. Both approaches can be considered as a late-stage functionalization; easily available -pyridyl-substituted diarylamines are used as the precursors.